资源简介
mp3read and mp3write for matlab(for windows),MATLAB两函数mp3read和mp3write,MATLAB两函数mp3read和mp3write
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代码片段和文件信息
%% MP3 reading and writing
%
% These function mp3read and mp3write aim to exactly duplicate
% the operation of wavread and wavwrite for accessing soundfiles
% except the soundfiles are in Mpeg-Audio layer 3 (MP3) compressed
% format. All the hard work is done by external binaries written
% by others: mp3info to query the format of existing mp3 files
% mpg123 to decode mp3 files and lame to encode audio files.
% Binaries for these files are widely available (and may be
% included in this distribution).
%
% These functions were originally developed for access to very
% large mp3 files (i.e. many hours long) and so avoid creating
% the entire uncompressed audio stream if possible. mp3read
% allows you to specify the range of frames you want to read
% (as a second argument) and mp3read will construct an mpg123
% command that skips blocks to decode only the part of the file
% that is required. This can be much quicker (and require less
% memory/temporary disk) than decoding the whole file.
%
% mpg123 also provides for “on the fly“ downsampling at conversion
% to mono which are supported as extra options in mp3read.
%
% For more information including advice on handling MP4 files
% see http://labrosa.ee.columbia.edu/matlab/mp3read.html
%% Example usage
% Here we read a wav file in then write it out as an MP3 then
% read the resulting MP3 back in and compare it to the original
% file.
% Read an audio waveform
[dsr] = wavread(‘piano.wav‘);
% Save to mp3 (default settings)
mp3write(dsr‘piano.mp3‘);
% Read it back again
[d2sr] = mp3read(‘piano.mp3‘);
% mp3 encoding involves some extra padding at each end; we attempt
% to cut it off at the start but can‘t do that at the end because
% mp3read doesn‘t know how long the original was. But we do so..
% Chop it down to be the same length as the original
d2 = d2(1:length(d):);
% What is the SNR (distortion)?
ddiff = d - d2;
disp([‘SNR is ‘num2str(10*log10(sum(d(:).^2)/sum(ddiff(:).^2)))‘ dB‘]);
% Do they look similar?
subplot(211)
specgram(d(:1)1024sr);
subplot(212)
plot(1:5000d(10000+(1:5000)1)1:5000d2(10000+(1:5000)));
% Yes pretty close
%
% NB: lame followed by mpg123 causes a little attenuation; you
% can get a better match by scaling up the read-back waveform:
ddiff = d - 1.052*d2;
disp([‘SNR is ‘num2str(10*log10(sum(d(:).^2)/sum(ddiff(:).^2)))‘ dB‘]);
%% External binaries
% The m files rely on three external binaries each of which is
% available for Linux Mac OS X or Windows:
%
% *mpg123* is a high-performance mp3 decoder. Its home page is
% http://www.mpg123.de/ .
%
% *mp3info* is a utility to read technical information on an mp3
% file. Its home page is http://www.ibiblio.org/mp3info/ .
%
% *lame* is an open-source MP3 encoder. Its homepage is
% http://lame.sourceforge.net/ .
%
% The various authors of these packages are gratefully acknowledged
% for doing all the hard work to make these Matlab functions possible.
%% Installation
% The
属性 大小 日期 时间 名称
----------- --------- ---------- ----- ----
目录 0 2007-07-30 15:37 __MACOSX\
目录 0 2007-07-30 15:37 __MACOSX\mp3readwrite\
文件 82 2007-03-30 17:11 __MACOSX\mp3readwrite\._.DS_Store
文件 1544 2009-05-19 15:17 license.txt
目录 0 2007-07-30 15:36 mp3readwrite\
文件 6148 2007-03-30 17:11 mp3readwrite\.DS_Store
文件 3728 2007-02-04 23:09 mp3readwrite\demo_mp3readwrite.m
目录 0 2007-02-04 23:14 mp3readwrite\html\
文件 10834 2007-02-04 23:14 mp3readwrite\html\demo_mp3readwrite.html
文件 6212 2007-02-04 23:14 mp3readwrite\html\demo_mp3readwrite.png
文件 63096 2007-02-04 23:14 mp3readwrite\html\demo_mp3readwrite_01.png
文件 195072 2002-04-16 13:35 mp3readwrite\lame.exe
文件 377484 2002-01-02 22:56 mp3readwrite\lame.glnx86
文件 469376 2006-12-30 17:39 mp3readwrite\lame.mac
文件 490312 2007-02-04 21:32 mp3readwrite\lame.maci
文件 71680 2004-10-23 16:20 mp3readwrite\mp3info.exe
文件 22896 2001-07-17 05:30 mp3readwrite\mp3info.glnx86
文件 60364 2004-09-08 21:09 mp3readwrite\mp3info.mac
文件 35032 2007-02-04 20:37 mp3readwrite\mp3info.maci
文件 10042 2007-07-30 15:36 mp3readwrite\mp3read.m
文件 4870 2007-07-26 15:09 mp3readwrite\mp3write.m
文件 139264 2004-10-23 16:20 mp3readwrite\mpg123.exe
文件 159824 2000-02-02 23:31 mp3readwrite\mpg123.glnx86
文件 124076 2004-01-30 02:08 mp3readwrite\mpg123.mac
文件 122464 2007-02-04 19:37 mp3readwrite\mpg123.maci
文件 829672 2007-02-04 20:16 mp3readwrite\piano.wav
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